This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The first goal of this project is to determine the SIV-specific cellular and humoral immune responses and virus evolution in breast milk of SIV-infected or SIV-vaccinated rhesus monkeys. The second goal of the project is to determine the magnitude of the vaccine-elicited, SIV-specific immune response in breast milk following systemic vaccination.